Abstract:
The Center for Responsible Nanotechnology has a primer on the topic, and recommend a system of international nano-arms control, with lots of oversight and verification:

"Conflict between nations killed millions in the last century. MNT-based conflict could be even worse. Nations attack when they feel threatened by others, or to satisfy internal political pressures including desperate domestic conditions. As discussed on our Dangers page, molecular manufacturing can easily lead to an unstable arms race—a very threatening situation. Even nations that are ostensibly allies may be uneasy about each other's ultimate intentions, and there are many combinations of powerful nations that maintain at best an uneasy truce. Unless nations can find some basis for trusting that MNT won't be used against them in unexpected ways, they will have no choice but to develop defensive, and probably offensive, nanotechnology. International MNT arms control, with strict and trustworthy verification, appears to be the best alternative."